1. Field of Invention
This invention relates to a road safety barrier having retainers for holding a wire rope or cable against a post or posts of the road safety barrier, and in particular but not exclusively to a retainer having a yieldable or frangible tab.
2. Discussion of Related Art
Conventional wire rope road safety barriers comprise a series of spaced apart posts that are provided with hooks or notches for supporting the wire rope which may weave sinuously around the posts or in parallel thereto. These road safety barriers typically consist of two or more ropes (normally two to five) along the side of the barrier and perhaps one or two ropes lying within slots positioned at the top of the posts. Wire rope safety barriers serve to deflect impacting vehicles back into the carriageway or to decelerate the impacting vehicle as it slides along the barrier. Posts within the impact zone tend to collapse on impact and as a consequence, the wire rope becomes detached from the posts. Conventional road safety barriers have the problem that the ropes on vehicle impact become detached from the barrier for a significant distance up and downstream of the impact area. The detachment arises as shock wave, sometimes referred to as ‘whip’, from the vehicle impact travels along the wire ropes of the barrier. Consequently, there is a significant degree of rope deflection or separation from this whip which leads to an unpredictable impact characteristic of the road safety barrier on vehicle impact. Over-deflection or separation of the ropes outside of the impact zone due to the whip reduces the effectiveness of the barrier's ability to restrain impacting vehicles. Moreover, the force of the whip itself can lead to unpredictable behaviour of the wire ropes on collapse which can compromise the ability of the barrier to restrain the vehicle.